Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h, w = map(int, input().split())
m = [['#']*(w+2)] + [['#']+list(input())+['#'] for _ in range(h)] + [['#']*(w+2)]

d = [(1, 0), (0, 1), (-1, 0), (0, -1)]
q = deque([(1, 1, 1)])
m[1][1] = '@'
ans = -1
while q:
    x, y, c = q.popleft()
    if x == h and y == w:
        ans = c
        break
    for dx, dy in d:
        nx, ny = x+dx, y+dy
        if m[nx][ny] == '.':
            q.append((nx, ny, c+1))
            m[nx][ny] = '@'

if ans != -1:
    for i in range(1, h+1):
        for j in range(1, w+1):
            if m[i][j] == '#':
                ans += 1
    ans = h*w - ans

print(ans)